It is already known from the U.S. Pat. No. 4,437,355 granted to Andre Bordat Mar. 20, 1984 to provide a bevel gear power transmitting gear train having a right angle bevel gear drive in which the power input gear is mounted so that it floats slightly in the directions perpendicular to its axis of rotation. This automatically balances the power that is transmitted directly to the power output gear with the power that is transmitted indirectly via a set of "loose" or idler gears.
The Bordat mechanism, however, has a major drawback in the way that the axial components of the forces that automatically balance the power transmitted directly and indirectly to the power output gear are suppressed so that the power input gear does not move axially More specifically, the Bordat mechanism employs an elongated swivel pin (20) that passes through the power input gear (2) and its integral stub shaft (1) and into the interior of the gear train where an integral bearing bushing at the inner end of the swivel pin (20) is journalled on a cross shaft (23) that is attached to the power output gear (3) and extends through the idler gear (5). The power input gear (2) and its integral stub shaft (1) are retained axially on the elongated swivel pin (20) by angular contact ball bearings (21) and (22) inside the stub shaft (1).
This swivel pin arrangement uses considerable space inside the gear train and consequently the Bordat mechanism is not suitable for many applications, such as those that require narrow gear spacing or concentric power shafts extending through the interior space of the gear train. The swivel pin arrangement also limits the torque and speed capabilities of the Bordat mechanism because small angular contact ball bearings to rotatably support and axially retain the power input gear (2) and its integral stub shaft (1) and because a plain journal bearing is used to axially retain the swivel pin (20). Consequently the Bordat mechanism is not well suited for high speed, high power applications such as gas turbine engine drives that use spiral bevel gears.